Epithelioid angiomyolipoma of the kidney.

Epithelioid angiomyolipoma is a recently recognized variant of angiomyolipoma, which is characterized by the presence of polygonal cells with densely eosinophilic cytoplasm and varying degrees of nuclear atypia. Only a relatively small number of cases of epithelioid angiomyolipoma of the kidney have been reported in the literature. We report a case of epithelioid angiomyolipoma of the kidney that occurred in a 38-year-old woman. The tumor was composed of diffuse sheets of epithelioid cells, adipocytes and only scattered thick-walled blood vessels. The epithelioid cells had pleomorphic and hyperchromatic nuclei with densely eosinophilic cytoplasm. Hemorrhage, necrotic foci and clusters of foamy macrophages were present. HMB-45, CD117 (c-kit) and CD68 were detected in the epithelioid cells. There was no expression of cytokeratin, epithelial membrane antigen or desmin. The patient showed no evidence of recurrence or metastatic disease 9 months after nephrectomy.